The Imaging core (Core D) is comprised of a centralized cutting-edge microscopy facility, absolutely essential to the research goals of Projects in this P01 application and housed within the Center for Biologic Imaging (CBI) (www.cbi.pitt.edu) of the University of Pittsburgh. All investigators have made, and continue to make, heavy use of the CBI for facility-specific imaging methodologies. Evidence of the longevity of this use is seen in co-authored publications between the PI and staff of the Core (Watkins, St. Croix, Stolz) and PI's of the individual projects. The imaging specialties afforded by CBI include all ultrastructural electron microscopy (transmission electron microscopy, scanning electron microscopy, immune-electron SEM and TEM), light and fluorescence microscopy (macro dissecting light and fluorescence, epi-fluorescence, confocal scanning and multi-photon imaging), live cell microscopy (transmitted light and fluorescence) and fluorescence specialties like FRET, FRAP spectral analysis and ratiometric imaging. Also critical to data processing, a wide range of image analysis software and technical assistance is available to program investigators.